Gray Screen Error Please Help

Newbie, first post. Just followed the 3.1-4.1 mod tutorial and modded my virgin Wii that was on OS 4.0u which went perfectly and everything works except:

Using USB Loader GX (USB_Loader_GX-ULNR-r688.wad) to play Mario Super Sluggers. The game starts and allows us to play but about 5 minutes into it, the game freezes and the screen shows a blank gray screen. I believe the Wii locks too. Have to hold the power key in for 5 seconds to restart it.

I have turned on the 002 fix, but haven't played with any other settings. What suggestions do you have? Any settings? Or should I try a newer version of USB Loader GX? If so, which one?

I haven't tried the game using Neogamma yet--really like the USB Loader interface and the kids can navigate that easier. Thanks for any help / guidance!
J